The present invention relates to method and apparatus for trimming flashing which forms when plastic members are fused together. More particularly, the present invention relates to method and apparatus for trimming flashing without the need for removing the joined members from the joining equipment and transporting the members to a remote trimming/polishing station.
High speed automatic equipment for joining frame components which have been cut to size and supplied to the equipment for fabricating a frame or a frame-like structure, are well known in the art.
The typical operation is to provide plastic frame members which have been processed preparatory to the joining operation to form a frame, for example. Although machines of this nature are capable of simultaneously joining substantially all four corners of a frame structure, a description will be given herein of the manner in which two frame members forming one corner of the frame structure are joined, it being understood that the other three corners are formed in a substantially identical manner and are also performed substantially simultaneously with the corner joining operation described hereunder.
The frame members, which have previously been precision mitred to form a corner, are placed in the machine, typically referred to as a conventional 4-point welder structure, are positioned within clamping devices and are moved towards one another so that the surfaces to be joined engage a locator plate which typically provides a gap of the order of one quarter inch (0.25″) between the surfaces to be joined. The clamping assemblies clamp the frame members in place so that the surfaces to be joined extend a given distance beyond their clamping devices in a direction toward the opposite clamping device.
The clamping devices are then moved apart by an amount sufficient to enable the locator plate to be withdrawn. After the locator plate is withdrawn, a heated plate is placed in the gap region between the surfaces to be joined. The clamping devices then move the frame members towards one another causing the surfaces to be joined to engage opposing surfaces of the heated plate which heats the surfaces to be joined to a level sufficient to heat a marginal end portion of each frame member to a softened or molten state. This is accomplished by adjusting/controlling the temperature of the heated plate and the time interval during which the engaging surfaces of the frame member are in contact with the heated plate to achieve the desired molten state.
Thereafter, the clamping assemblies are moved to separate the frame members to enable the heated plate to be withdrawn. After the heated plate has been removed from the region between the heated, molten surfaces, the clamping members are moved to bring the heated molten, surfaces of the cooperating frame members into intimate engagement. This action causes the molten surfaces to fuse together as they undergo cooling. In addition, the bringing together of the frame members causes some of the molten material to be squeezed out from the region between the joined ends of the engaged frame members, whereby the molten material squeezed out from between the joined surfaces, forms an undesirable flashing.
After the frame members have cooled sufficiently, the frame is removed from the clamping assemblies.
The frame assembly is removed to a separate location from the four 4-point welding equipment to undergo trimming and polishing, necessitating: removal of the completed frame; transportation to a trimming/polishing station; clamping of the frame at the trimming/polishing station; and performing the trimming/polishing operations. In addition, the techniques presently used for trimming/polishing the flashing typically requires a large amount of manual labor to obtain frames having the desired clean, aesthetic appearance in the regions of the joined corners.